<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        header{
            background-color: red;
            height: 50px;
        }
        .main_1{
            background-color: green;
            height: 500px;
        }
        .main_1 nav{
            height: 100%;
            width: 30%;
            background-color: aliceblue;
            float: left;
        }
        .main_1 article{
            height: 100%;
            width: 50%;
            background-color: yellow;
            float: left;
        }
        .main_1 aside{
            height: 100%;
            width: 20%;
            background-color: gray;
            float: left;
        }
        footer{
            background-color: aqua;
            height: 50px;
        }
    </style>
</head>
<body>
    <main class = "main">
        <header></header>
        <main class="main_1">
            <nav></nav>
            <article></article>
            <aside></aside>
        </main>
        <footer></footer>
    </main>
</body>
</html>